As an alternative to cans, products which generate gases, typically either roasted and ground coffee or roasted whole bean coffee, are often packaged in soft packages without applying a vacuum; these packages are typically known as pillow bags. Pillow bags are desirable in that they are easier to handle and more lightweight than cans and, as the product is used, the bags may be compressed to reduce the amount of space needed to store them. However, there are several drawbacks associated with pillow bags.
One problem with pillow bags is that newly packaged coffee tends to generate a mixture of gases inside the bag, mainly carbon dioxide, which causes the bag to become swollen and eventually burst, rendering the package unsellable. This problem has been ameliorated to some degree by the inclusion of a degassing valve in the bag which releases gas from the bag when a certain internal pressure is reached. The valve then closes when pressure returns to an acceptable level. Such valves are disclosed, for example, in U.S. Pat. No. 5,515,994 to Goglio and U.S. Pat. No. 4,000,846 to Gilbert. The design of these valves is typically such that the bag must completely fill with gas before sufficient internal pressure is reached to open the valve. Since such bags must necessarily have a headspace, i.e., a space within the bag above the product, and since the bags can freely expand, the headspace will fill with gas, giving it a swollen appearance by the time it is placed on the shelves of a retail store. This swollen appearance tends to be very undesirable to the consumer.
Another problem that is encountered with pillow bags is that because the bags are packaged in containers, such as rectangular boxes held closed with tape, adhesive or the like, there is a likelihood that if a knife is used to open the container, one or more bags may inadvertently be cut, rendering them unsellable. Still another problem is that since the bags are generally packaged such that they do not completely fill the container, they may bounce freely within the container during shipping and handling, causing cracks and holes to form in the bag film, allowing air to leak into the bags. The oxygen in this air causes staleness in the product long before the intended shelf-life has expired.
Accordingly, the need exists for a packaging system for ventable pillow bags containing gas generating products which reduces the amount of gas build-up in the headspace of the bags and prevents damage to the bags during shipping and handling.